In recent years the Transient Receptor Potential (TRP) family of ion channels has emerged as global mediators of sensory signaling and important molecular targets in the search for the causes of many neurological disorders. Mutations in TRP channels, or excessive TRP channel activity are associated with a variety of diseases and conditions, ranging from an early childhood neurodegenerative disease to chronic pain, skeletal malformation and kidney disease. Despite these broad roles, the contribution of TRP channels to mechanosensation remains poorly understood. Recently, the Montell laboratory has identified a Drosophila TRP channel, TRPy, that appears to play a role in proprioception, or the sensing of body position. The goal of this multidisciplinary work is to further explore, from a behavioral, molecular, and biophysical perspective, the role(s) of TRPy in fly mechanosensory transduction. To this end, I will first assess the behavioral effects of deleting TRPy by testing for defects in coordination. I will test trpy null mutant flies in locomotor assays as our preliminary data indicate that these flies are defective in negative geotaxis (climbing). To expand on these findings I will conduct a goal-driven gap-climbing assay as a more detailed test for coordination impairments. I will also test mutant larvae for defects in mechnosensation and in proprioceptive function (touch and rollover assays). My second aim seeks to examine the expression pattern of TRPy in greater detail, and determine the cellular requirement for this protein. This will be accomplished by raising anti-TRPy antibodies and performing immunostaining. Using the expression pattern data as a guide, I will then use the GAL4-UAS system to study the cellular requirement for trpy by expressing UAS-TRPy with pan-neuronal, chordotonal, and pan-muscle drivers. The functionality of TRPy in these locations will be assessed through rescue of the aforementioned coordination defects. In my third aim I will directly test TRPy for mechanosensitivity using patch-clamp techniques. I will initally perform in vitro biophysical analyses on TRPy expressed in tissue culture cells. Our patch-clamp setup is designed to test for channel activation in response to membrane stretch. For the in vivo studies, | will conduct electrophysiology recordings directly from the mechanosensory organs where trpy is expressed. This multidisciplinary study should provide new insights into the roles of TRP channels in fly mechanosensation.